This invention relates to a heater unit for an automotive vehicle air conditioner.
Some automotive vehicle air conditioners have a series combination of a blower unit, a cooling unit, and a heater unit. In the case of a high-grade air conditioner which allows independent control of front and rear parts of the vehicle interior, a heater unit tends to be large. To increase the free space in the vehicle interior, it is desirable for the heater unit to be compact.
It is advantageous that several kinds of air conditioners are adaptable to automotive vehicles of the same type. In this case, the heater unit of the high grade air conditioner would preferably have the same configuration as other air conditioners, since a common configuration would enable any heater unit to be attached to the vehicle body without changing the design of the vehicle body. Heater units for lower-grade air conditioners are simpler in structure than heater units for the higher-grade air conditioner. Accordingly, to make the heater units for both types of air conditioner compatible, it is preferable for the high-grade heater unit to be compact.